The present invention relates to a sealed rolling bearing such as a sealed four row, tapered roller bearing used for example for a roll neck bearing in a rolling mill in the steel manufacturing equipment, particularly to a sealed rolling bearing wherein the pressure change (negative pressure) in the bearing space is refrained so as to prevent fluid such as water and foreign matter such as scale from entering the bearing space, thereby preventing the function of the seal member adjacent the end faces of the bearing from being degraded and the lubricant from being deteriorated, rust from being produced in the bearing, and the performance of the bearing from dropping.
For the bearing which may be used in the environment where fluid such as water may splash on it , for example for the roll neck bearing of the rolling mill in the steel manufacturing equipment, the sealed rolling bearing having a seal device incorporated therein is used as disclosed in Japanese patent publications Toku Ko Sho 60-14933 and Toku Ko Sho 61-12130 etc.
FIG. 6 shows an example of the sealed rolling bearing, specifically a four row, tapered roller bearing having a seal incorporated therein. Incidentally, FIG. 6 shows only the upper half of the four row, tapered roller bearing in cross section with the shaft omitted therefrom.
The sealed roller bearing illustrated comprises two first outer rings 1, a second outer ring 2, two inner rings 3, a number of rollers 4, located in four rows in the bearing space S between the first and second outer rings 1, 2 and the inner rings 3 and a cage in each of the four rows for rotatably supporting the rollers 4, therein, so that the inner rings 3 are rotated within the first and second outer ring 1, 2. Seal holders 7 are located at the opposite ends in the axial direction of the bearing to hold an elastic seal 8 adjacent the first outer rings 1, respectively. The elastic seals 8 have lips 8a, respectively, which come into contact with the outer peripheral surface of the inner rings 3 at the opposite ends in the axial direction of the bearing. Consequently, lubricant is kept within the bearing space S, and it is possible to prevent fluid such as water and foreign matter such as scale from entering the bearing space S from outside.
A seal space V is formed at the portion where the inner rings 3 come into contact with each other, and located adjacent the inner diameter surface of the inner rings 3. The seal space V may be located adjacent the outer diameter surface of the inner rings 3.
An intermediate seal member 9 is incorporated within the seal space V. This intermediate seal member 9 is to prevent fluid such as water and foreign matter such as scale from entering the bearing space S for example during mounting and dismounting of a roll (not shown).
The intermediate seal member 9, for example shown in FIG. 7(a), comprises a core metal 9a for shape-keeping and an elastic member 9b for sealing in the seal space V. The intermediate seal member 10, shown in FIG. 7(b), comprises a seal body 10a having a base portion and a leg portion in a T-shape in cross section and an elastic member 10b provided on the inner diameter side of the base portion of the seal body 10a, wherein the shape of the seal space V is different, but its function is substantially the same to that of FIG. 7(a).
There is a problem, however, in the prior art sealed rolling bearing as mentioned above that it could not sufficiently prevent the entering of water etc. under a condition of large temperature change.
For example, in the case where the sealed rolling bearing is used as a roll neck bearing for rolling mill in the steel manufacturing equipment, the sealed rolling bearing supports a roll the rotation number (rpm) of which frequently changes.
Specifically, the high speed rotation, low idling rotation and stoppage are repeated in the roll, so that the temperature in the bearing space S of the sealed rolling bearing changes corresponding to the respective conditions. Accordingly, expansion and contraction of the air etc. within the bearing space S are repeated, and the air in the space which has expanded at a higher temperature escapes through the elastic seals 8 at the end faces of the bearing, and then the bearing, space S of the sealed rolling bearing is placed under negative pressure at a lower temperature.
Moreover, in the condition where water exists more or less within the interior, at the inside temperature of 100xc2x0 C. or higher, the water becomes steam in expansion, and upon temperature drop, a large negative pressure is produced.
The negative pressure within the bearing space S accelerates wear of the elastic seals 8 to worsen the function of the elastic seals 8. Accordingly, fluid such as water and foreign matter such as scale can enter the bearing space S through the elastic seals 8. Consequently, problems may be produced, e.g. lubricant is deteriorated and rusting occurs in the bearing, resulting in the premature drop in bearing performance.
The present invention is invented taking into consideration the above mentioned situation.
An objective of the present invention is to provide a sealed rolling bearing wherein by refraining the pressure change (negative pressure) within the bearing space, fluid such as water and foreign matter such as scale are prevented from entering the bearing space, so that the function drop of the seal member adjacent the end faces of the bearing, the deterioration of lubricant, the rusting in the bearing, the degradation in bearing performance are prevented.